Plastic composition comprising a vinyl resin and a bis-nu-substituted pyrrolidinone



Patented July 18, 1961 No Drawing. Original application Dec. 12, 1955,Ser.

No. 552,289. Divided and this application May 16, 1960, Ser. No. 43,969

3 Claims. ('Cl. 260-302) The invention is concerned with a novel groupof new bis-N-substituted pyrrolidinones and with certain compositionscontaining these compounds. Some of these compounds are useful asplasticizers for various plastic materials and particularly for vinylresins. Certain members of this class are also useful as monomers andcomonomers in the preparation of addition polymers. Others are useful inpreparing alkyd-type resins. In particular, these compounds are a groupof substituted bis-pyrrolidinones in which the two nuclei are connectedthrough their nitrogen atoms by means of certain divalent organicradicals.

The novel compounds of this invention have the following structuralformula wherein R is H, or a lower aliphatic hydrocarbon groupcontaining up to about eight carbon atoms, and R is an alkylene,oxalkylene, thialkylene or azalkylene group containing from two to abouttwelve carbon atoms. Exarnples of [lower aliphatic hydrocarbon groups,R, are the methyl, ethyl, allyl, propargyl, butyl, hexyl, hexenyl,Z-ethylhexyl and octyl groups. These groups are straight or branchchained and may be saturated or unsaturated. The divalent organicradical R when derived from an alkyl group, straight or branch chainedis called an alkylene group. It contains from two to about twelve carbonatoms. The carbon chain of said alkylene group is sometimes interruptedby one of the heterogroups --O, S, NH, S--S-, or NHNH--. The R group isthen called an oxalkylene group when it contains oxygen, a thialkylenegroup when it contains sulfur, or an azalkylene group when it containsnitrogen. The two nuclear pyrrolidinone ring nitrogens are each attachedto to dilferent carbon atoms of said R group. These carbon atoms aresometimes adjacent and sometimes more widely separated. When the R groupis an oxalkylene, a thialkylene or an azalkylene group, each carbon atomof said R group is attached to no more than one heterogroup, except forthe carbon atoms attached to the pyrrolidinone nitrogen atoms which arenot further attached to heterogroups but to one or more carbon atoms.Structures embodying two oxygen, sulfur or nitrogen atoms attached to analiphatic carbon atom are in general somewhat unstable, particularlyunder acidic conditions and are therefore less applicable for the usesfor which the valuable products of this invention are suited. A furtherpractical limitation on the structure of the R group is that it containless than about four heterogroups. The diamines corresponding to saidstructures are largely available or can be synthesized by methodsfamiliar to those skilled in the art. However, the diamines containingfour or more heterogroups are not commercially available and they cannotbe prepared readily by simple and unequivocal methods. Thus, the abovedescription of the R group can be summarizedby saying that R is adivalent organic id radical containing from two to twelve carbon atomsand selected from the group consisting of an alkylene group, anoxalkylene group, a thialkylene group, and an azalkylene group whereinsaid groups contain less than four heterogroups and such that no carbonatom is attached to more than one atom selected from the groupconsisting of oxygen, sulfur and nitrogen. To further illustrate theconfiguration of the R group in the foregoing structural formula, someexamples of alkylene, oxalkylene, thialkylene and azalkylene groups aregiven below.

| CH3 CH3 In the foregoing structural formula when R is H the productsare dibasic acids. These dibasic acids are use fill in preparing alkydresins by reaction with various types of polyhydroxy compounds and, insome cases, polyhydroxy compounds and monobasic acids by methods wellknown in the art. Polyhydroxy compounds useful in preparing resins ofthis type include ethylene glycol, propylene glycol, trimethyleneglycol, diethylene glycol, glycerol, pentaerythritol, sorbitol, etc.When the polyhydroxy compound contains three or more hydroxyl groups,the extent of cross-linking is modified by the incorporation ofmonobasic acids in the reaction mixture. Ordinarily fatty acids areemployed. These may include oleic acid or linoleic acid which conferdrying-oil properties on the resin or saturated fatty acids such asbutyric acid, palmitic acid, or stearic acid. These alkyd resins havenovel properties stemming from the unusual structure of the valuabledibasic acids of this invention employed in their preparation.

When R in the foregoing structural formula is a lower aliphatichydrocarbon group, the products are diesters useful as plasticizers forvarious plastic materials, such as synthetic rubber, polyvinyl andpolyvinylidene halide polymers and copolymers, and in particular,polyvinyl chloride resins, and vinyl chloride-vinyl acetate copolymers.Plastic compositions of this nature generally comprise the resin and newplasticizer in the relative proportions of about 50 to resins and 5 to50% plasticizer. Certain members of this series are preferred for thisuse. For example, when R is a methyl group, the diesters are solidswhich are generally water soluble. While such materials can be used incertain instances as plasticizers, it is generally preferred that theplasticizer be a high boiling, water insoluble liquid. Highly usefulplasticizers with these properties are found in the fully saturated compounds in this series commencing with about the dibutyl' ester. Ingeneral, the most useful compounds have a total of at least about tencarbon atoms in the two R groups and the R group. As the homologousseries is ascended, the plasticizing ability of these esters remainshigh until the R and R groups contain a total of about 28 carbon atomsat which point their compatability with vinyl resins has decreased to apoint of minimum usefulness.

When R in the foregoing structural formula contains acetylenic bonds theproducts are diesters useful as plasticizers-stabilizers forpolyvinylhalide polymers and copolymers and in particular, polyvinyl chlorideresins, polyvinylidene chloride resins and ,various copolymerscontaining these monomers. It is thought that these materials possessthis added advantage of being stabilizers due to the fact that theacetylenic bond present absorbs any hydrogen halide evolved during theaging and use of the polymer. An example of this class of pyrrolidinonesis the product obtained by the reaction of dipropargyl itaconate,described in copending application Serial No. 563,440, filed February 6,1956, with a diamine.

The compounds of this invention in which terminal olefinic groupings arepresent in the R radical are diesters which can be polymerized orcopolymerized. By terminal olefinic group is meant the group CHs= CPolymerization of these materials to thermosetting plastic substancesuseful in the preparation of cast molded or laminated articles isaccomplished by the usual techniques for preparing addition polymerswhich involves polymerization of the monomer or mixture of monomerseither in bulk, emulsion, suspension or solution processes employing theusual type of peroxide initiators such as benzoyl peroxide, di-t-butylperoxide, t-butylhydroperoxide, etc. Useful copolymers are obtained byusing bispyrrolidinones of this type with such comonomers as styrene,methyl acrylate, vinyl acetate, etc. The resulting copolymers arethermosetting and heat and solvent resistant. Desirable eifects areobtained by the use of these bis-pyrrolidinones as comonomers over awide range of proportions. For example, a proportion ofbis-pyrrolidinone as low as 3% in the copolymer frequently has a usefuleffect on the softening point of the product. Olefinic esters of thistype can also be polymerized alone to novel and useful products.

The valuable diesters of this invention are prepared by allowing theappropriate itaconic diester to react with the desired diamino compound.The following equation represents this process wherein R is a loweraliphatic hydrocarbon group containing up to about eight carbon atomsand R has the same meaning as above.

The reaction between the diamine and itaconic diester generally sets inimmediately after the reactants are mixed and is manifested by theevolution of heat. Some combinations of diesters and diamines react morevigorously than do others, but in general even in the less reactivecases, an exothermic reaction takes place without delay. It is generallydesirable to apply external cooling so that the reaction temperaturedoes not exceed about 80 C. Above this temperature the reaction maybecome so vigorous as to be impossible to control and decomposition ofthe product or expulsion of the contents of the reaction vessel mayoccur. No solvent is required in carrying out this process. After thereaction subsides the alcohol that is a by-product of the condensationis stripped in vacuo. In some cases, it is convenient to remove theby-product alcohol by steam distillation.

If it is desired to purify these valuable products, vacuum distillationis a suitable method. The lower members of the series can be distilledin ordinary laboratory or plant-sized vacuum distillation equipment. Forthe higher members of the series a short path apparatus and high vacuumsare required e.g. 0.01 mm. of mercury or less. For some purposes, thevaluable products of this invention are in a usable form after removalof the volatile impurities as described above, and further purificationis not required. A number of the itaconic acid diesters used as startingmaterials are commonly available compounds. Others can be prepared bythe application of known esterification procedures. A process that canfrequently be advantageously employed involves heating itaconic acid andthe desired alcohol with a small amount of p-toluenesulfonic acidcatalyst in an inert solvent such as benzene.

The reactants in this process are preferably employed in stoichiometricproportions, that is'two moles of ester are employed per mole ofdiamine. A slight excess, say about ten percent, of the ester componentcan be tolerated but an excess of the diamine component is to be avoidedsince some mono-pyrrolidinone product is produced as well as highmolecular Weight by-products when an excess of the amine is present.Such materials are very difficult to separate from the desiredbis-pyrrolidinone product.

Various diamino compounds are readily available and are useful in thisprocess. Among the commercially available diamines that have beenemployed are ethylenediamine, propylenediamine, trimethylenediamine,hexmethylenediamine, diethylenetriamine (NH CH CH NHCH CH NH andethylene bisoxypropylarnine (NH CH CH OCH CH OCH CH CH NH Other aminesthat can be readily prepared by methods well known in the art includel,IO-decamethylenediamine, 1,12 and 2,l1-dodecamethylenediamine,3,3-thio-bis-propylamine and 3,3-dithio-bis-propylamine. The lattermaterial'which contains sulfur is readily obtained from 3-mercaptopropylamine by mild oxidation to the disulfide. Treatment withan aminoalkyl halide in the presence of a base yields a similar type ofdiamine containing one sulfur atom. Other diamines that are applicablein the synthesis of the valuable bis-pyrrolidinones of this inventionwill occur to one skilled in the art.

The above dibasic acids, that is when R is H in the original structuralformula, are readily prepared by the selective hydrolysis of thecorresponding diesters whose preparation was just described. Theselective hydrolysis can be carried out in a variety of systemscontaining various acidic and alkaline reagents. Organic solvents aresometimes employed, but aqueous systems are preferred and particularlythose containing barium hydroxide wherein the amount of hydroxidecharged is just sufficient to neutralize the carboxyl groups arisingfrom hydrolysis of the ester functions without affecting the lactamrings. Thus the diesters are useful not only as plasticizers, but alsoas intermediates in the preparation of the corresponding acids.

The following examples are given to further illustrate this valuableinvention. However, they are not to be considered as limiting it in anyway. In fact, resort may be had to many widely varying embodimentswithout departing from the spirit and scope thereof.

EXAMPLE I Dimethyl itaconate, 316 g. (2 moles), and 60 g. (1 I EXAMPLEII The dialkyl itaconates and diamines listed in Table I were similarlyemployed in the preparation of valuable diesters of this invention. Theproperties of the resulting products are listed in- T able II.

Table I.Diamines and dialkyl itaconates Dialkyl Itaconates Diamines CH1H1NRN Ha [I Ethylenediamine C O-C 01R TrimethylenediamineHexamethylenediamine CH1C 01R Ethylene bis-oxypropylamineDiethylenetriamine Dodecyl; Iso-octyl; Allyl; Propargyl.

6 EXAMPLE IV The product of Example I, (0.5 mole), was refluxed with a25 percent excess of barium hydroxide in 1 l. of water for two hours.The amount of barium hydroxide employed was based on the amount requiredto hydrolyze the two ester functions and leave the two lactam ringsintact. At the conclusion of the heating period, the solution was cooledand the barium precipitated by treatment with sulfuric acid. The bariumsulfate was filtered and the cake washed with hot water to remove asmall amount of the bis-pyrrolidinone di-acid that precipitated with it.The combined filtrate and washes were then concentrated in vacuo asbefore and the product collected. It was a white crystalline solid. Itwas recrystallized from water. The purified product had a melting pointof 23 l4 C. This di-acid is soluble in hot water but is insoluble inmost organic solvents. The product contained 7.06 milequivalents of acidper gram (theory 7.04).

EXAMPLE V In order to illustrate the method of preparing the valuableplastic compositions of this invention as well as to demonstrate theutility of these valuable diesters as plasticizers,ethylene-bis-4-carbobutoxy-Z-pyrrolidinone (Example II, R=CH CH andR'=n-C H and ethyl- Table II.-Pr0perties of reaction products ofdiamines and dialkyl itaconates 11 11 CHr-C CCH:

\ NRN RO1O- H-CH1 CH2 HCOzR' Analysis Boiling Point C. R R (mm. of Hg)19 Calculated Found 0 H N C H N 60.6 8.15 7.08 60.0 7.82 7.10 62.2 8.556.60 61.8 8.54 6.61 (n)O11H11 66.2 9.46 5.51 65.7 9.10 5.67CH3(OH2)3CHCH2C2H5 66.2 9.46 5.51 65.8 9.35 5.88 CH3CHT- (n)C H 1.484269.6 10.40 4.52 67.5 9.44 5.21

CH2CH2' (is0)CaH11 1.4816 66.2 9.46 5.51 66.2 9.58 5.64 CH1CH1CH1 CH1 6114 13). 55.2 6.82 8.60 55.1 6.87 8.40 CH1(CH1)4CH:- CHa-. 264(0.5)1.5000 58.7 7.66 7.65 58.4 7.49 7.61 CH3(CH7)4CH3- (iso)O H Voltatilec0m51)Jonents-removed 1.4822 68.1 10.0 4.96 68.4 10.10 4.84 a. 20CHCH;CH;OCH9 CH3- 160 (0.2) 1.4995 56.2 7.56 6.55 56.2 7.64 7.08

CHrCH2CH2QCHI CH1CH1CH1OCH1 (l1)C4Hqvolagifilg cpfiponents removed1.4894 60.9 8.66 5.45 60.7 8.75 5.12 -oH1oH1oH1 o oH1 OH1GH1NHCH1OH1-..CH3- volagr' lg cggponents rem ved (1) (1) (1) (1) (1) (1) -oH.on1-onFonom- 2ao o.4 1.5095 59.4 6.59 7.69 59.4 6.86 7.19

1 Dark amorphous product, not analyzed.

EXAMPLE III ene-bis-4-carbooctoxy-Z-pyrrolidinone (Example II, R=

5 CH CH and R'=n-C H were formulated at vari- Dimethyl itaconate, twomoles, and one mole of diethylenetriamine were mixed and the temperatureof the mixture immediately rose to 80 C. At this point, the reaction wascooled to room temperature in an ice bath. The reaction mixture wasstripped in vacuo as before. Methanol, which had been evolved in thecourse of the reaction, was recovered in the distillate. On cooling theproduct solidified to a dark amorphous solid. This product was watersoluble. Its infrared absorption was very similar to the abovebis-pyrrolidinones in the region 5.7- 9.5,u.

An alkyd-type of polyester was prepared by heating 28.4 g. (0.1 mole) ofthe dibasic acid of Example IV together with 8.4 g. (0.11 mole) ofpropylene glycol, toluene, and p-toluenesulfonic acid. Provision wasmade to remove water of esterification as formed. The reaction wascontinued until the rate of removal of water became negligible, at whichtime the reaction mixture was cooled and immiscible toluene decanted.The heavy oil, after neutralization of the catalyst, proved to be thedesired polyester.

EXAMPLE VII A polyester was prepared by heating in a nitrogen atmospherea mixture of 28.4 g. (0.1 mole) of the dibasic acid of Example IV, 13 g.(0.1 mole) of itaconic acid,

16.8 g. (0.22 mole) of propylene glycol, toluene, p-tolu enesulfonicacid, and hydroquinone. Provision was made to remove water eliminatedduring esterification as formed. The reaction was continued until therate of.

removal of water became negligible, at which time the reaction mixturewas cooled. Titration showed the esterification to be 99% complete. Theheavy cloudy oil which resulted was diluted with methyl ethyl ketone,the catalyst neutralized with the calculated volume of 0.2 N sodiumhydroxide, the solution washed with water, and dried over anhydrousmagnesium sulfate. The product was obtained as a very viscous materialby evaporation of the solvent. Cross-linking to yield a rigid solidproduct was achieved by the peroxide catalyzed copolymeriza tion witheither styrene or dibutyl itaconate. Other copolymers can be prepared ina similar fashion.

EXAMPLE VIII In order to demonstrate the production of plastic castingsfrom a valuable bis-pyrrolidinone diester of this invention containingterminal olefinic groupings, N,N'-ethylene-bis-(4-carboallyloxy)2-pyrrolidinone alone and mixed in variousproportions with styrene and with methyl methacrylate was thermallypolymerized using 0.5-1%

of benzoyl peroxide as the initiator. The liquid monomers, 10 g. sampleseach of pure bis-pyrrolidinone and each composition, were placed inglass vials containing in some cases 50 mg. and others 100 mg. ofbenzoyl peroxide and heated in an oven in which the temperature wasincreased from C. to 100 C. during about six days. The vials were thencracked and removed from the plastic castings contained therein. Thecompositions of the mixtures employed are listed in Table III. Allyielded hard and tough castings. Those containing styrene were somewhatcloudy in appearance. All of the others were transparent.

Percent N,N'-ethylene-bis- Percent Percent Percent (l-parboallyloxy)2-pyr Styrene Methyl Benzoyl rolidinone Methacrylate Peroxide Thisapplication is a divisional application of copending application SerialNo. 552,289 filed December 12, 1955, now abandoned.

What is claimed is:

1. A plastic composition comprising a vinyl resin and a compound of theformula 1 wherein R is a lower aliphatic hydrocarbon group containing upto about 8 carbon atoms and R is a divalent .organic radical containingfrom 2 to 12 carbon atoms and selected from the group consisting ofalkylene, oxalkylene, thialkylene and azalkylene wherein the last threemembers of said group contain less than 4 hetero groups selected fromthe group consisting of O, S,

NH-, --S-S-, and NHNH and such that no carbon atom is attached to morethan one atom selected from the group consisting of oxygen, sulfur andnitrogen.

2. The plastic composition of claim 1 wherein said compound of theformula comprises from 5 to by weight of said composition.

3. The plastic composition of claim 2 wherein the total number of carbonatoms in the two R groups and the R group of said compound of theformula is from about 10 to about 28.

No references cited.

1. A PLASTIC COMPOSITION COMPRISING A VINYL RESIN AND A COMPOUND OF THEFORMULA